Method and device for through-hole plating of substrates and printed circuit boards

ABSTRACT

A method and apparatus for through-contacting flexible substrates  1,  in particular circuit boards, having electrically conductive contact zones  4, 41  present on two opposing surfaces  1   a   , 1   b  of the substrate provides that a cut  11  is produced obliquely to the surfaces of the substrate in the area of the contact zones, and the two substrate areas  20, 30  adjoining the oblique cut are moved past each other until they lock behind each other. Moving them past each other is effected by a ram  12,  by the action of compressed air  13,  by applying a vacuum  14  or by a driving hook  15  fixed to the cutting tool. The two steps of producing the cut and moving the two substrate areas adjoining the cut past each other are effected in a common processing station, preferably in a single operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/EP02/12774, filed Nov. 14, 2002.

FIELD OF THE INVENTION

This invention relates to a method and apparatus for through-contactingflexible substrates, in particular circuit boards, having electricallyconductive contact zones disposed on two opposing surfaces of thesubstrate, whereby a cut is produced by means of a cutting tool throughthe substrate obliquely to the surfaces of the substrate in the area ofthe contact zones, and the two substrate areas adjoining the oblique cutare moved past each other until they lock behind each other. Thisachieves the result that they touch the contact zones disposed on theopposite surfaces of the substrate, that is, the contact zone on theupper side of the substrate touches the contact zone on the underside ofthe substrate.

DESCRIPTION OF THE BACKGROUND ART

Such a method is described in the unpublished patent application DE 10122 414.1. Compared to conventional through-contacting methods by whichthrough-contacting is effected by punching or drilling a through holeand inserting a conductive contact sleeve or pouring in a conductivepaste (EP-A-0 884 973), this method is fundamentally simpler. Thesurfaces of the substrate can be leveled again by subsequent lamination,which at the same time stabilizes the electrical connection between thetwo contact zones. No additional conductive material is required forproducing the contact since the contact zones press firmly against eachother due to the internal stress of the flexible substrate.

Such a substrate or such circuit boards are normally integrated as acard inlay into IC cards or chip cards (identity cards, credit cards,cash cards, etc.) and frequently form a separate layer of the card body.On one side of the circuit board there can be for example an integratedcircuit formed by the conductive layer and having further electronicdevices, while the conductive layer on the opposite side of the circuitboard is formed for example as an antenna coil for noncontacting datainterchange and energy transfer with external devices, which iselectrically connected with the integrated circuit through the circuitboard. This electrical connection through the circuit board is generallydesignated “through-contacting.”

Instead of IC cards, the substrate can also be used in the context ofthe present invention for tags, stickers and similar security elementswith antenna coil technology and/or electronic inlays.

It proves to be problematic in this method that the two working steps tobe performed in succession, namely the oblique cut and the urgingthrough of the two substrate areas adjoining the cut (hereinafter alsodesignated “contact tabs” or “through-contacting tabs”), are impreciseand lead to high reject rates. Internal tests with the method thereforerequired a high expenditure of manual work.

SUMMARY OF THE INVENTION

It is the problem of the present invention to specify a concrete andreliable, simplified method for through-contacting circuit boards andthe like as well as an apparatus for carrying out the method.

Therefore, the through-contacting tabs produced by the oblique cut arenot pushed past each other manually; this is done mechanically by meansof a separate ram or by means of compressed air or by applying a vacuumor automatically during production of the oblique cut by a driving hookfixed to the cutting tool. Single or several of these measures can alsobe combined with each other. The use of said mechanical aids permits themethod to be automated and the reject rate to be reduced.

A special advantage is to be seen in the fact that the mechanical aidsfor urging through the through-contacting tabs can be combined with thecutting tool for producing the oblique cut in a common processingstation. This makes it in particular possible to perform both processingsteps with the substrate position unchanged, so that the mechanical aidsfor urging through the through-contacting tabs always act on thesubstrate at an exactly predetermined position relative to thepreviously provided cut.

It is particularly advantageous if the two steps required forthrough-contacting are effected in a common operation. This goal can beattained for example by the cutting tool with a driving hook fixedthereto by the cutting tool first being pushed through the substrateobliquely to the substrate plane, and one of the two thereby producedthrough-contacting tabs being urged behind the other through-contactingtab for example by a driving hook fixed to the cutting tool upon furtheradvancing of the cutting tool.

The two steps of producing the cut and urging through the tab can alsobe integrated into one operation when applying compressed air and/or avacuum.

Even the use of a separate ram for urging one contacting tab throughbehind the other contacting tab can be integrated into the working stepof producing the oblique cut. In this case the contacting tabs are urgedpast each other by the ram before the cutting tool is withdrawn from theoblique cut. The cutting tool is preferably realized as a knife bladewhich is resilient perpendicular to the knife blade plane.

In accordance with a special embodiment of the invention, the cuttingedge of the cutting tool is serrated and has at least one tooth. Thisprevents the knife from slipping after being placed on the flexiblesubstrate and accordingly improves the precision of through-contacting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be described by way of example withreference to the accompanying drawings, in which:

FIGS. 1 a and 1 b show the front and back of a flexible substrate,

FIG. 2 shows two embodiments of an inventive apparatus forthrough-contacting the substrate in a side view,

FIGS. 3 a and 3 b show a substrate through-contacted by means of theapparatus according to FIG. 2 in cross section and in a plan view,

FIG. 4 shows an embodiment of the inventive apparatus according to FIG.2,

FIGS. 5 a and 5 b show a substrate through-contacted by means of theapparatus according to FIG. 4 in cross section and in a plan view,

FIG. 6 shows two further embodiments of an inventive apparatus forthrough-contacting the substrate in a side view, and

FIG. 7 shows a cutting tool with a serrated cutting edge.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 a shows the front of a substrate 1 suitable for incorporationinto a card body. On this side of the substrate a conductive layer 2 isshown in the form of a coil for noncontacting data and energy exchangewith an external device. The coil 2 disposed on this side of thesubstrate 1 has the contact zones 4 and 5, the contact zone 5 beingprovided for contacting with an IC module. A further contacting of thecoil with the IC module is effected via the contact zone 6 which isconnected by a through-contacting at the site 8 with a secondelectrically conductive layer 3 in the form of a second coil on the backof the substrate 1 (FIG. 1 b). A further through-contacting of the sametype connects the contact zone 4 with the coil 3 at the site 7. Theassociated contact zones of the coil 3 on the back of the substrate aremarked as 61 and 41 in FIG. 1 b.

FIG. 2 jointly shows two embodiments of an inventive apparatus forcarrying out the through-contacting. The two embodiments have in commonthat in a processing station the substrate 1 lies on a soft base 10, forexample a rubber mat, and, with the position of the substrate unchanged,both a cut 11 is produced obliquely to the surfaces 1 a, 1 b of thesubstrate 1 and the through-contacting tabs 20, 30 formed by the cut areurged past each other until the tab 30 locks behind the other tab 20, asshown in FIG. 3 a.

The cut 11 in the substrate 1 is preferably produced at a 45° anglerelative to the substrate surfaces 1 a, 1 b.

The step of moving the two through-contacting tabs 20, 30 past eachother is effected by means of a driving hook 15 on the knife 9 inaccordance with the first embodiment shown in FIG. 2. To this end, theknife 9 mounted displaceably in the knife holder 20 is first pushedforward in the axial direction to produce the cut 11. Further advancingthe knife 9 causes the driving hook 15 to come in contact with thecontact tab 30 located on the right of the cut 11 in FIG. 2 and urge itback behind the contact tab 20 located on the left of the cut 11 in FIG.2 so that the two contact tabs lock behind each other (FIG. 3 a).

In accordance with the second embodiment shown in FIG. 2, a ram 12 whichis movable up and down in the direction of the arrow is used instead ofthe driving hook 15 for moving the two through-contacting tabs 20, 30past each other. In this case, the cut 11 is first produced by the knife9 by the knife 9 being advanced in its axial direction and then, beforeor after the knife 9 has been moved back to its initial position, theram 12 is used to again urge the contact tab 30 located on the right ofthe cut 11 behind the contact tab 20 located on the left of the cut 11.The ram 12 has in this case a comparatively small cross section andurges with this cross section only the central area of the right contacttab 30 under the left contact tab 20.

In a plan view, both embodiments result in a through-contactedconfiguration as shown in FIG. 3 b. Therefore, the contact tabs 20, 30overlap with their surfaces 1 a, 1 b (FIG. 3 a) only in a central areaof the cut 11. The thereby produced contact area between the contactzones 4 of the coil 2 and the contact zone 41 of the coil 3 is shownhatched in FIG. 3 b.

After through-contacting is completed in the processing station, thesubstrate 1 can be removed from the processing station and for examplebe completed to form a plastic card in a laminating process with furtherplastic layers and optionally further electronic devices.

Instead of the ram with a comparatively small cross section as shown inFIG. 2, a ram extending along the total length of the cut 11 can also beused. The driving hook 15, which is preferably comparatively small andplaced in the center of the knife 9 in the embodiment according to FIG.2, can also optionally extend over the total width of the knife 9. Inthis case, urging the right contact tab 30 through behind the leftcontact tab 20 leads to tearing of at least the urged through contacttab 30 at the two cut ends. To avoid this, the alternative embodimentsto the apparatus from FIG. 2 as shown in FIG. 4 provide that the knife 9has lateral cutting elements 9 a, or the ram 12 has lateral cuttingelements 12 a, which ensure that a clean cut 11 a is producedperpendicular to the transverse extension of the cut 11 either uponproduction of the cut 11 by the cutting elements 9 a or upon urging ofthe contact tabs past each other by the cutting elements 12 a. Thethrough-contacting tab 30 then has a typical tab form in the strictersense, as indicated in FIG. 5 a on the right contacting tab 30 urgeddownward out of the substrate plane. Said contact tab 30 is separated onthree sides from the substrate 1 by the cuts 11 and 11 a and connectedwith the substrate 1 on only one side. FIG. 5 b again shows a plan viewof the area of the through-contacting produced by the apparatus fromFIG. 4. The concretely contacted surface between the contact zones 4 and41 is again hatched.

FIG. 6 again shows jointly in one picture two further embodiments of aninventive apparatus for carrying out the method. In this case, the rightcontact tab 30 is moved past the left contact tab 20 by compressed air13 directed to the front 1 a of the contact tab 30, and/or by a vacuumapplied to the back 1 b of the contact tab by a vacuum pump 14. In thiscase, the base 10 can be a firm base, since the cut 11 is guided intothe suction port of the vacuum pump 14, and the through-contacting tab30 located on the right of the cut 11 is also moved into said suctionport when moving past the contacting tab 20 located on the left of thecut 11.

FIG. 7 shows a special embodiment of the knife 9 having a serratedcutting edge. In the embodiment specifically shown, the cutting edge ofthe knife 9 has a single tooth 9 b which serves to prevent the knife 9from slipping after being placed on the surface 1 a of the substrate 1.

1. A method for through-contacting flexible substrates (1) havingelectrically conductive contact zones (4, 41; 6, 61) disposed on twoopposing surfaces (1 a, 1 b) of the substrate (1), whereby a cut (11) isproduced by means of a cutting tool (9) through the substrate obliquelyto the surfaces (1 a, 1 b) of the substrate (1) in the area of thecontact zones (4, 41), characterized in that the two substrate areas(20, 30) adjoining the oblique cut (11) are moved past each other untilthey lock behind each other, the step of moving them past each otherbeing performed in one operation with the production of the cut.
 2. Amethod according to claim 1, characterized in that the adjoiningsubstrate areas (20, 30) are moved past each other by means of at leastone of a separate ram (12) or a driving device (15) disposed on thecutting tool.
 3. A method according to claim 1, characterized in thatthe adjoining substrate areas (20, 30) are moved past each other bycompressed air (13) or production of a vacuum (14).
 4. A methodaccording to claim 1, characterized in that the two steps of producingthe cut and moving the two substrate areas past each other are performedwith the substrate position unchanged.
 5. A method according to claim 1,characterized in that the oblique cut (11) is produced at an angle of45° to the substrate surfaces (1 a, 1 b).
 6. An apparatus for carryingout the method according to claim 1, comprising a cutting tool (9) forproducing a cut (11) through a substrate (1) obliquely to two opposingsurfaces (1 a, 1 b) of the substrate, and a device (12; 13; 14; 15) formoving two substrate areas (20, 30) adjoining the cut (11) past eachother and locking them behind each other, characterized in that thecutting tool (9) and the locking device (12; 13; 14; 15) are disposed ina common work station.
 7. An apparatus according to claim 6,characterized in that the locking device comprises a ram (12).
 8. Anapparatus according to claim 6, characterized in that the locking deviceuses compressed air (13) for moving the two substrate areas adjoiningthe cut past each other.
 9. An apparatus according to claim 6,characterized in that the locking device uses a vacuum (14) for movingthe two substrate areas adjoining the cut past each other.
 10. Anapparatus according to claim 6, characterized in that the locking devicecomprises a driving hook (15) fixed to the cutting tool (9).
 11. Anapparatus according to claim 6, characterized in that the cutting tool(9) has a cutting edge with at least a tooth (9 b).
 12. An apparatusaccording to claim 6, characterized in that the cutting tool (9)comprises a knife blade which is resilient perpendicular to the knifeblade plane.